1 files changed, 16 insertions, 52 deletions

diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 42e3d1ed802c..cb9ab54146cc 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -444,56 +444,22 @@ void map_stub_pages(int fd, unsigned long code,
         }
 }
 
-void new_thread(void *stack, void **switch_buf_ptr, void **fork_buf_ptr,
-                void (*handler)(int))
+void new_thread(void *stack, jmp_buf *buf, void (*handler)(void))
 {
-        unsigned long flags;
-        jmp_buf switch_buf, fork_buf;
-
-        *switch_buf_ptr = &switch_buf;
-        *fork_buf_ptr = &fork_buf;
-
-        /* Somewhat subtle - siglongjmp restores the signal mask before doing
-         * the longjmp.  This means that when jumping from one stack to another
-         * when the target stack has interrupts enabled, an interrupt may occur
-         * on the source stack.  This is bad when starting up a process because
-         * it's not supposed to get timer ticks until it has been scheduled.
-         * So, we disable interrupts around the sigsetjmp to ensure that
-         * they can't happen until we get back here where they are safe.
-         */
-        flags = get_signals();
-        block_signals();
-        if(UML_SETJMP(&fork_buf) == 0)
-                new_thread_proc(stack, handler);
-
-        remove_sigstack();
-
-        set_signals(flags);
+        (*buf)[0].JB_IP = (unsigned long) handler;
+        (*buf)[0].JB_SP = (unsigned long) stack +
+                (PAGE_SIZE << UML_CONFIG_KERNEL_STACK_ORDER) - sizeof(void *);
 }
 
 #define INIT_JMP_NEW_THREAD 0
-#define INIT_JMP_REMOVE_SIGSTACK 1
-#define INIT_JMP_CALLBACK 2
-#define INIT_JMP_HALT 3
-#define INIT_JMP_REBOOT 4
-
-void thread_wait(void *sw, void *fb)
-{
-        jmp_buf buf, **switch_buf = sw, *fork_buf;
-
-        *switch_buf = &buf;
-        fork_buf = fb;
-        if(UML_SETJMP(&buf) == 0)
-                UML_LONGJMP(fork_buf, INIT_JMP_REMOVE_SIGSTACK);
-}
+#define INIT_JMP_CALLBACK 1
+#define INIT_JMP_HALT 2
+#define INIT_JMP_REBOOT 3
 
-void switch_threads(void *me, void *next)
+void switch_threads(jmp_buf *me, jmp_buf *you)
 {
-        jmp_buf my_buf, **me_ptr = me, *next_buf = next;
-
-        *me_ptr = &my_buf;
-        if(UML_SETJMP(&my_buf) == 0)
-                UML_LONGJMP(next_buf, 1);
+        if(UML_SETJMP(me) == 0)
+                UML_LONGJMP(you, 1);
 }
 
 static jmp_buf initial_jmpbuf;
@@ -503,23 +469,21 @@ static void (*cb_proc)(void *arg);
 static void *cb_arg;
 static jmp_buf *cb_back;
 
-int start_idle_thread(void *stack, void *switch_buf_ptr, void **fork_buf_ptr)
+int start_idle_thread(void *stack, jmp_buf *switch_buf)
 {
-        jmp_buf **switch_buf = switch_buf_ptr;
         int n;
 
         set_handler(SIGWINCH, (__sighandler_t) sig_handler,
                     SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGALRM,
                     SIGVTALRM, -1);
 
-        *fork_buf_ptr = &initial_jmpbuf;
         n = UML_SETJMP(&initial_jmpbuf);
         switch(n){
         case INIT_JMP_NEW_THREAD:
-                new_thread_proc((void *) stack, new_thread_handler);
-                break;
-        case INIT_JMP_REMOVE_SIGSTACK:
-                remove_sigstack();
+                (*switch_buf)[0].JB_IP = (unsigned long) new_thread_handler;
+                (*switch_buf)[0].JB_SP = (unsigned long) stack +
+                        (PAGE_SIZE << UML_CONFIG_KERNEL_STACK_ORDER) -
+                        sizeof(void *);
                 break;
         case INIT_JMP_CALLBACK:
                 (*cb_proc)(cb_arg);
@@ -534,7 +498,7 @@ int start_idle_thread(void *stack, void *switch_buf_ptr, void **fork_buf_ptr)
         default:
                 panic("Bad sigsetjmp return in start_idle_thread - %d\n", n);
         }
-        UML_LONGJMP(*switch_buf, 1);
+        UML_LONGJMP(switch_buf, 1);
 }
 
 void initial_thread_cb_skas(void (*proc)(void *), void *arg)